diff --git a/zaza/openstack/charm_tests/mysql/tests.py b/zaza/openstack/charm_tests/mysql/tests.py
index c5e3f1821..830985b9d 100644
--- a/zaza/openstack/charm_tests/mysql/tests.py
+++ b/zaza/openstack/charm_tests/mysql/tests.py
@@ -21,6 +21,7 @@
 import re
 import tempfile
 import tenacity
+import yaml
 
 import zaza.charm_lifecycle.utils as lifecycle_utils
 import zaza.model
@@ -615,7 +616,7 @@ def _get_password_from_keystone_leader():
             'list-service-usernames',
             action_params={}
         )
-        usernames = json.loads(action.data['results']['usernames'])
+        usernames = yaml.safe_load(action.data['results']['usernames'])
         logging.info("... usernames: %s", ', '.join(usernames))
         self.assertIn('keystone', usernames)